1. Field of the Invention
This invention relates to a process of manufacturing sheet metal elements or strip having a catalytic surface structure, in which a mixture containing skeleton powder and Raney alloy powder in a ratio of 1:3 to 3:1 is applied to a starting sheet metal element or starting strip and bonded thereto by roll cladding and is subsequently sintered in a reducing atmosphere at temperatures above 600.degree. C., and the soluble component of the Raney alloy is dissolved out by a treatment with an alkaline or acid solution, and to the use of the resulting sheet metal element or strip having a catalytic surface structure as an electrode in electrolysis or as a catalyst in chemical reduction processes.
2. Discussion of the Prior Art
Double-skeleton catalyst electrodes, also known as DSC electrodes, have a high electrical conductivity and a high catalytic activity and for this reason can be used as electrodes in various types of electrolyzers, as electrodes in fuel elements and as catalysts for chemical reactions in which Raney catalysts are usually employed.
Such compact DSC electrodes have the disadvantage that when made in a thickness of a few tenths of a millimeter, which is adequate from the aspect of catalytic activity, they lack an adequate mechanical strength. On the other hand, an unreasonably large amount of catalyst will be required if such electrodes are made in a thickness which is adequate from the aspect of mechanical strength.
It is known that this disadvantage can be avoided in that a compact or porous metal substrate is coated with catalytic material. To that end, a mixture of a so-called skeleton material, serving as a carrier, and of Raney alloy is applied to and then pressed or rolled onto the metal substrate and sintered at temperatures above preferably 600.degree. C. in a reducing atmosphere, and the soluble component of the Raney alloy is finally dissolved out (Austrian Patent Specification No. 206,867).
The process just outlined is of advantage if the catalyst mixture is consolidated on the substrate by the application of pressure. This requires the application of a pressure of an order of 1000 kg/cm.sup.2 so that only DSC electrodes which are small in area can be manufactured with a reasonable equipment expenditure. Such small electrodes cannot be used or can be used only with difficulty, particularly in electrolyzers. Whereas even DSC electrodes large in area can be made if the catalyst mixture can be consolidated as it is bonded to compact metal surfaces by roll cladding, such operation is impracticable because it has been found that by the roll cladding the mixture of skeleton material and Raney alloy is pushed off the metal surface so that any catalyst layer which can be applied in this manner will be extremely thin and cannot be employed with useful results.
It is an object of the invention to provide a process for the manufacture of sheet metal elements or strip having a catalytic surface structure a process which process avoids the known disadvantages, particularly those mentioned hereinbefore, and particularly permits the manufacture of DSC electrodes large in area and can be carried out with a low equipment expenditure.